class Person {
  id: number;
  name: string;
  age: number = 18;
  
  constructor(id: number, name: string) {
    this.name = name;
    this.id = id  
  }
  
  introduce(): string {
    return `hello i am ${this.name} and i am ${this.age} years old`
  }
}

let p = new Person(1,"jaja");

console.log(p.introduce());
